The use of Insulating Concrete Forms (ICFs) is well accepted as a superior building construction technology. Briefly, an ICF is an expanded plastic, usually polystyrene, form comprising two spaced apart panels. The forms are assembled into a hollow vertical wall into which concrete is poured thereby creating a concrete wall. Unlike wood or steel forms, the ICF remains in place and becomes a permanent part of the building providing insulation that contributes to energy efficiency, lower noise, and environmentally responsible practices. There are a large number of design considerations for ICFs not the least of which is ease in constructing the hollow vertical wall with minimum labor costs.
Another consideration for the design of an ICF includes the overall size of the form. The larger the size of the form, the less number of forms are required to build a wall of a certain height and width and thus less labor is required to assemble the forms into the hollow vertical wall. However, because of the bulk of ICFs, in general, a countervailing consideration with respect to the size of the form is the shipping costs. Concrete walls constructed using ICFs may be anywhere from four inches in thickness to 24 inches in thickness. Typical wall thicknesses are 4, 6, 8 and 10 inches. In a typical ICF, the panel may be on the order of several inches of thickness. The panels are typically rectangular with the longer axis of the form horizontally oriented. A form manufactured and sold by American Polysteel, LLC, located in Albuquerque, N.M. is two feet high and four feet wide. It will therefore be seen that if a form is shipped ready to use, the overall form may be 2×4 feet (height and width) and between 10 and 30 inches in thickness depending upon the thickness of the concrete wall to be constructed. Thus, the volume of the form may be on the order of from 8 to 20 cubic feet. Since shipping costs are in part based upon the volume (as opposed to the weight) of the freight, one way of reducing the volume of the form is to ship the form in a “knocked-down” condition and assembling the form on site. An example of a knock-down flat panel form is shown in FIG. 1.
When panels are shipped in a knocked-down condition, the panels are assembled by inserting a structural member between the two panels to hold the panels in spaced apart relation during pouring of the concrete. After the concrete has set, the structural member is embedded in the concrete and thus holds the panels in snug relation to the faces of the concrete wall. These structural members are referred to in the ICF industry as “ties.” Ties may be of a wide variety of designs and construction including different types of material. The term “tie” is therefore a generic term for an object that provides the function of maintaining the panels in spaced apart relation.
There are various desirable features in a well-designed ICF tie used in a knocked-down form. The tie must be appropriately anchored in the panels so as to maintain the panels in the desired position thereby defining the thickness of the concrete wall. As wet concrete is poured, the concrete, particularly on the forms at the lowest level of the hollow wall, subjects the tie to considerable force by pushing the two panels away from one another. The tie assembly, defined as the combination of the tie and the anchor members secured to the panels must be capable of withstanding these considerable forces without separating, i.e., rupturing the integrity of the wall. It is also desirable to provide ties that can be used to support horizontal reinforcing bars (rebars) that are embedded in the concrete wall. The ties may be of various material as may be chosen by one having ordinary skill in the art. It is also desirable that the knocked-down type of ICF can be quickly and easily assembled at the job site. Still another consideration is that the ties which engage the anchors in the opposed panels during assembly of the form at the job site is relatively foolproof so as to avoid errors, such as improper tie insertion into the anchors in a manner such that the tie and anchors inadvertently become disengaged while concrete is poured.
None of the ties in the prior art provide some or all of these features.